DK201570085A1 - Sealing a bore or open annulus - Google Patents

Abstract

Disclosed is a method for use in restricting or sealing a bore. A tubular is expanded in the bore to cause the tubular to split and be extended towards a wall of the bore. A straddle is located within the tubular so as to extend across the region of the tubular which has been split, and expanded to seal the split in the tubular. Also disclosed is apparatus comprising one or more expansion tools and a straddle, for use in sealing or restricting a bore. The apparatus may be used in conjunction with a tubular as disclosed herein, having one or more weak zones adapted to preferentially split under the action of an expansion tool.

Description

SEALING AND BORE OR OPEN ANNULUS

The present Invention 'relates to a method for restricting or sealing an annulus, and in particular to sealing or restricting an open annulus around a tubular In a bore.

Background of the invention

It is a common requirement in the field of oil and gas production to restrict or isolate a bore or an annulus. For example, in a producing well. It may be required to seal a region suffering from water breakerough, or during drilling or artificial lift operations, it may be required to isolate porous rock formations in which fluids are lost. A well-known method for sealing or restricting fluid flow through an annulus is to run a packing tool into a bore, which can be expanded to provide a seal. However, there is a limit to the amount by which a packing tool is able to expand, in addition, packing tools cannot be run into a tubular to seal around that tubular, as might be required to isolate a portion of a producing well suffering from wafer breakthrough, for example, it is also known to seal a bore by injecting a sealing substance such as concrete or epoxy through perforations in a tubular. However, using injection methods, it may be difficult to control where the sealant flew, and only limited control may be possible over the amount of sealant infected or the portion of an annulus which is sealed. If Is also known for injected sealant to leak Into rock formations and fall to seal the bore, or for sealant to be eroded or washed away by flow regimes. gyfmcMMiiMQgaa

According to a first aspect of the invention, there is provided a method for use in restricting or sealing a tore comprising; expanding a tubular which is located in the bore to cause the tabular to split and be extended towards a waif of the bore; locating a straddle within the tubular which extends across the region of the tubular which has been split; and expanding the straddle to seal the split in the tubular.

The method may comprise expanding a tubular which is located in a bore to cause the tubular to spill and be extended in engagement with a wall of thé-borél Accordingly, the method may provide for sealing a bore.

The drill may be a well bora, or the drill may be defined by a casing, liner or a further tubular. The tubular may be located within an open bore such that tubular member is extended towards or in engagement with the face of the open bore. The method may involve expanding a tubular into compliant engagement with a, boro (such as an eccentric bore).

The rnctliod may provide for sealing of the annulus between the tubular and the bore such that fluid flow along said annuius is prevented or restricted.

The method may comprise spitting a length of the tubular. The method may comprise causing the tubular to split axially, or generally axially along a length of the tubular.

The tubular may be split along all, or part of the region which is expanded For example, a region of the tubular which has been expanded and split matically at each end to transitional regions of the tubular -which- have been expanded and which have not been split (which may each extend In turn to a region -of the tubular which has not been expanded .or split).

The tubular may comprise a single tubular member or may comprise a tubing string formed by multiple tubular members connected together end-to-end.

The tubular may be perforated. The perforations, may be slots, add the tubular may comprise slotted tubing, The tubular may, for example, comprise production tubing:, sand screen, or tubing for wellbore stimulation, such as controlled acid jet (CAJ) liner.

The method may comprise restricting or sealing the bore and sealing one or more perforations in the tubular.

The method may comprise locating an expansion fool within the tubular and using the expansion tool to expand and axially split the tubular.

At least a portion of the expansion tool may be. configured to radially expand, so as to expand and split the tubular.

At least a .portion of the expansion too! may be configured to radially contract, following expansion. The expansion tool may be a -reusable 'expansion tool, for example to remove the expansion tool from, or reposition the expansion tool within the tubular.

An expandable portion of the tool may be adapted to comply with the internal profile of flia tubular.

The expansion tool may be configured to limit the extension of the tubular.

The expandable portion may be operable to radially expand to a predetermined circumference.

The expansion tool may comprise a reinforcing structure configured to provide reinforcement to an expandable portion, such as a bladder,. The reinforcing structure may be configured to limit expansion of the expandable portion. The reinforcing structure may surround the expandable portion.

The reinforcing structure may include protection from tearing or perforation of the bladder.

The expansion fee may be expanded to cause the tubular to split and to be extended in engagement with a casing or another tubular, and: the-reinforcing structure may be configured to limit expansion as no? to expand and / or spill the casing or other tubular.

The expandable portion may comprise a bladder and the method may comprise inflating the bladder to cause expansion, spitting and extension of the tubular. The bladder may be expanded hydraulically. The expansion tool may be described in co-pending international application WO 2012/140512.

The expansion tool may comprise an explosive charge, to detonate and cause expansion and splitting of the tubular. The explosive charge may be detonated to cause expansion of an expandable portion of the expansion fool, such as a bladder.

The method may comprise locating a straddle which extends across the region of the tubular which has been played. The method may comprise ideating a straddle which extends across the region of the tubular which has been split and across transitional regions of the tubular which has been expanded but not split.

The method may comprise expanding the straddle so as to seal perforations within the tubular, The s; i addle may, for example, provide for sealing bi perforations in the tubular to prevent fi-ds by passing the expanded and sealed section by flowing Info the tubular on one side of the expanded portion and exiting back into the bore on the other side of the tubular.

The method may comprise using a bladder of an expansion tool as a straddle, by expanding the bladder with a settable medium (such as epoxy or cement) and setting the settable medium,

The method may comprise locating an expansion; tool within a tubular, which extends across a region of the tubular which has been split; and expanding the expansion tool (e.g. by expanding a bladder with a settable medium) to seal the split in the tubular.

The bladder may be provided with a cylindrical member extending therethrough. The cylindrical member may function as a conduit for injecting a settable medium into the bladder (e.g., through perforations in the cylindrical member) and / or the cylindrical member may function to guide drilling: through the bladder.

The method: may company hosting the straddle within the tubular, extending across the region of the iubma ^ wn ^ h has been split, using an expansion tool.

The method may comprise locating a straddle positioned around an expansion tool and using the expansion tool to expand the straddle and sea! the split in the tubular.

The expansion tool used to expand the straddle may be the expansion tool used to expand and split the tubular. The method may comprise expanding and splitting the tubular with a lind expansion tool, locating a second expansion tool across the region of the tubular which has been split and expanding the second expansion tool to seal the split in the tubular.

The method may compose providing a sealing: arrangement between the straddle and the tubular. The straddle may comprise a sealing arrangement around and along some or all of the length of the straddle. The sealing arrangement may, for example, comprise a deformable or an elastomeric coating, or a sealant coating.

The straddle may be expanded to extend through the axial split in the tubular to engage the bore wall.

The method may be performed in a bore which is producing or in which production has been temporarily ceased e.g. in order for well stimulation or ln] ection to take place.

The method may be used to restrict or seal a bore having a substantially larger diameter than the tubular. The diameter of the bore wall may be at least 2δ% or at least 50% larger than the unexpanded tubular. The diameter of the bore may be up to twice as large as the unexpended tubular.

The method may comprise splitting a tubular along a weak zone, and / or expanding the tubular by banding around and along: a predefined zone of deformation.

The weak zone may comprise a frangible portion. The predefined zone of deformation may comprise a living hinge. The weak zone and predefined zone of deformation may focus splitting and deformation of the tubular, respectively, which will facilitate predictable: splitting and expansion of the tubular.

The method may comprise providing a tubular with a predefined zone of deformation and / or a weak zone .. The method may comprise providing a tubular with a weak zone and / or a predefined zone of deformation in situ.

The method may comprise weakening a zone of the tubular, and subsequently splitting the tubular along the weak zone. A weak zone and / or a predefined zone of deformation may be provided by the use of a perforation tool, cutting tool or the like.

The method may comprise providing a region of reduced wall thickness of the tubular, for example a line with a pattern of cavities or slots.

The method may comprise splitting a tubular along and beyond a weak zone. According to weak zones may provide a starting point for a split in the tubular. A length of the tubular may comprise more than one weak zone and / or more than one predefined zone of deformation. A length of the tubular may comprise more than one weak zone circumferentially spaced apart and / or axially spaced apart. A length of tubular may comprise? weak zones which are diametrically opposite sides of the tubular.

The method may comprise splitting a length of the tubular Into fragments and: extending the fragments into engagement with a waif of the bore.

The method may comprise retaining the fragments in engagement with the wall of the drill, and / or so as to prevent fragments, from failing to info the annulus around the tubular or into the tubular, for example by one or more bridges or tethers.

The tubular may comprise one or more bridges or tethers.

An expansion tool may comprise or function as a bridge or a tether. For example, expandable portion of an expansion tool may function as a bridge or tether, A bridge or a tether may be positioned around or against an expandable portion of an expansion fool.

The method may comprise detonating an explosive charge so as to inflate a bladder and split a length of the tubular into fragments.

The method may comprise further or Intermediate steps, as required, for example to position or reposition an expansion tool and / or the straddle.

According to a second aspect: the invention provides the use of an expansion tool in restricting or sealing a bore, by expanding a tubular which is located in the bore to cause the tubular to spit and be extended towards a wall of the bore. The expansion fool may also be used to expand a straddle which has been positioned so as to extend across the region of the tubular which has been split, so as to seal the split in the tubular. The expansion tool may be used in the method o! the first aspect. The invention also extends the use of an expansion comprising a bladder as a straddle, by expanding the bladder with a settable medium and setting the settable medium,

According to a third aspect of the Invention apparatus is provided for use in restricting or sealing a bore, the apparatus comprising: an expansion fool position within the boro located in the boro, and configured to expand the tubular; and causing the tubular to spill and be extended towards a wail of the bore; and a straddle posltionabie within the tubular and extending across a region of the tubular split by the expansion tool, the straddle configured to be radially expanded by an expansion tool to seal a split in the tubular.

The apparatus may comprise a first expansion tool, a straddle and a second expansion tool configured to radially expand the straddle.

The straddle may comprise corrugations or folds, The straddle may comprise a leaf arrangement. The straddle may fake the shape of an expandable bladder.

Tli © apparatus may comprise a downhole tool or a work string, the tool or work string comprising at last! one radially expandable portion and at least one .straddle.

The apparatus may comprise more than one straddle and / or more than two expansion tools. Thus, the apparatus may be used to expand, split and expand more than one part of a tubular and to expand a straddle to seal each said spilled

The apparatus may further comprise a tubular.

The tubular may be provided with one or more weak zones and / or one or more predefined zones of deformation,

The apparatus may comprise an arrangement for weaving a tubular, such as a perforator, or a cutting arrangement.

The apparatus may be used in the method of the first aspect.

According to a fourth aspect of the invention, there is provided a tubular having a weak zone extending axially along at least a portion of the length of the tubular, the weak zone adapted to preferentially split under the action of an expansion fool.

When expanded by an expansion tool, the tubular is adapted to split into a predicate less along the weak zone, A weak zone may extend parallel to a central axis of the tubular. A weak zone may extend along the entire length of the tubular, A weak zone may comprise a frangible region, A weak zone may comprise a region (e.g., a line or a strip) of reduced wail thickness. For example, a weak zone may comprise a line, or a slot pattern, or a series of cavities extending along a length of the tubular and partially through the wall of the tubular, A weak zone may comprise a series of perforations.

The weak zone may be adapted to fail without exposing sharp edges towards the inside of an expanded and split tubular. Thus, the risk of perforating an expansion tool including an inflatable bladder is reduced. For example, the tubular may be provided with an internal coating across the weak zone, such as an infernal coating of plastic material. In use, the Internal coating may deform or flow, so as to cover sharp edges.

The tubular may comprise a region of reduced thickness matter! extending to either side of the weak zone, which may bend outwardly under the action of an expansion fool.

The tubular may comprise a predefined zone of deformation extending axially along at least part of the length of the tubular, adapted to deform or bend where the tubular has been split and is further expanded, under the action of an expansion tool.

Bending · of a tubular around a predetermined zone of deformation may cause edges of a tubular along the split in the tubular to be pivoted away from each other, and thus away from an expanslon tooL

The tubular may comprise both a weak zone and a predefined zone of deformation, A weak zone and predefined zone of deformation may extend along the same length of tubular. A length of the tubular may comprise more than one weak zone circumferentially spaced apart and / or axially spaced apart. A predefined zone of deformation and weak zone may be diametrically opposite each other along at least a portion of the length of the tubular. A length of tubular may comprise weak zones which are diametrically opposite each other. A length of tubular having circumferentially spaced apart weak zones may comprise one or more weak zones or predetermined zones of deformation extending cireumferentiallyiy around the tubular (e.g. at the end of the circumferentially spaced apart weak zones):.

The tubular may comprise a bridge or a tether extending from a portion of the tubular along a length of the tubular having a weak zone, to a portion of the tubule without, a weak zone.

The bridge or tether may comprise a band or mesh secured to a wall (inside or outside of) the tubular.

The tubular may be perforated and may be provided with perforations along some or all of its length. The tubular may, for example, be slotted tubing or a CAJ liner, a weak zone, or a predefined zone of deformation, may, for example, comprise a series of perforations which are more closely spaced than the perforations away from the said weak zone.

According to a fifth aspect of the invention, there is provided a method for weakening a tubular comprising providing a weak zone extending axially along a portion or the length of the tubular.

The method may comprise providing a predefined zone of deformation associated with (e.g. diametrically opposite) the weak zone. A weak zone and / or a predefined zone of deformation may be provided by reducing the wall thickness of a region of the tubular. The method may comprise running a tool info the tubular, the fool is a chemical, mechanical or hydraulic cutting tool, and reducing the wail thickness of the tubular using the tool.

The weak zone and / or predefined zone of deformation may be provided in a tubular in a bore (e.g., in a wellbore).

Further preferred and optional features of each aspect of the Invention correspond to preferred and optional features of any other aspect of the invention.

Example embodiments of the invention will now be described with reference to the following figures in which;

Figure i shows apparatus for restricting or sealing a drill.

Figure 2 shows a schematic {a) side view and (fa) plan view along line A of an expansion tool at the end of a wotfc string positioned in a tutelar in a bore.

Figure 3 shows a schematic (&} side view and {b) plan view along line A of the expansion tool with the bladder radially expanded, and the tutelar expanded and split.

Figure 4 shows a schematic (a) side view and <b) plan view along line A of the expansion tool with the bladder subsequently deflated, and the tubular expanded and split

Figure S shows a schematic (a) side view and (b) plan view along line A of a straddle located across the expanded and split tubular and positioned around a further expansion tool.

Figure 6 shows a schematic (a) side view and (b). plan view along line A of the straddle expanded by the expansion tool, to seal the split In the tubular.

Figure 7 shows a schematic (a) side view and (b) plan view along line A of the seated tubular alter the expansion tool has been removed.

Figure 8 shows an alternative embodiment of apparatus for restricting or sealing a bore, comprising (a) a first expansion tool and (b) a second expansion tool.

Figure 9 shows a schematic side view of the second expansion tool of Figure 8 <b> positioned in a tubular across a region which has bean expanded and split.

Figure 10 shows a schematic side view of the second expansion tool used to seal the split tubular,

Figure 11 shows a schematic side view of the sealed tubular, 'with a channel drawn through the second expansion tool.

Figure © 12 shows a tubular provided with weak zones extending axially along its length.

Figure 13 shows a cross section of the tubular of Figure 12 through line D,

Figure 14 shows a cross section inheriting the tubular of Figure 12 through line D, which has beers expanded and split by an expansion tool

Figure © 1S shows a tubular provided with weak zones on diametrically opposite skies of the tubular.

Figure 18 shows a cross section of the tubular of Figure 15, along line E.

Figure 17 shows an expansion tool having an explosive charge, positioned in a bore within a tubular as shown in Figure 15,

Figure 18 shows the expansion tool and tubular of Figure 17. foliowing detonation Of th e explosive charge.

Figure 1 shows apparatus for use in restricting or sealing a bore. A first expansion tool 1 is secured to a work string 3. The first expansion tool 1 has, towards its downhole, an inflatable bladder 5 and a reinforcing member 7 in the bladder. Also on the work string is a second expansion tool 9. The second expansion too! 9 has a longer bladder II and reinforcing, member 13'than first expansion too! 1. A straddle 15 is located around the work string, over the second expansion tool 9.

The method by which the apparatus shown in Figure 1 is used to seal a .bore 19-will now be described with reference to i-hgums 2 to S.

Figure 2 shows a tubular 17 in an unlined bore 1.9, such as a wellbore extending the earth to Intersect a formation. The work string is run into the tubular so that the expansion tool 1 is positioned in the region of the drill to be sealed.

As shown in Figure 3, the bladder 5 is then hydraulically radially expanded within the tubular · 1'9,. to cause the tubular to split. The split 21 extends generally axially along a length 23 of the tubular 17, The split, region of the tubular is then extended towards and Into engagement with the wails of the bore 19 »under the action of the bladder. As best seen in Figure 3 (b), the walls of the split tubular 17 engage with the inner walls of the • bore 19 and extend around approximately 60% of the circumference of the bore. Transitional regions 25 of the tubular, at either end of the region 23 which have been split, are expanded by the bladder 5,

The bladder 5 of the first expansion too! 1 is then deflated, as shown in Figure 4, An area 27 of the inner face of the bore 19, extending along the region of the tubular 23 which has been split, is open and fluid communication is possible: between the bore and the inside of the tubular 17, as generally indicated in Figure 4a by arrows C.

As shown in figure 5, the work string is then run further into the bore in direction 8, so as to locate the straddle 15 within the tubular across the region 23 of the tubular which has been spit. The straddle is provided with corrugations 18 running: along its length, which are visible. In cross section In Figure 5 (b),

As shown in Figure 6, the bladder 11 of the second expansion tool 9 is hydraulically expanded so as to expand the straddle 15 and seal the split In the tubular. As can be seen in Figure 6a, the straddle 15 is expanded Into engagement both with the transitional regions 25 and the split region 23 of the tubular 17. As can be seen in Figure 8b, in the spelled region 23 of the tubular 17, the straddle 15 Is expanded into engagement with both the. Inner face '29 of the tubular and the area 27 of the inner face of the drill IS, Thus, the straddle seals the spilled 21 In the tubular and the straddle and the expanded and split tubular together seal the bore. The bladder 11 of the second expansion tool 9 is then deflated and the work string is recovered from the tubular (Figure?}.

Figure.8 shows an alternative .embodiment of apparatus used in restricting or sealing a bore. Features common to the apparatus shown in Figures 1 to 7 are labeled with the same reference numerals, incremented by 100. A first expansion tool 101 is secured to a work string 103 (Figure 8 (a)), The first expansion tool 101 has , towards its: downhole end an Inflatable bladder 105 and a reinforcing member 107 in the-bladder. The first expansion tool 101 may be run into a tubular and used to expand and split the tubular, in the manner described above with reference to tool 1,

The i-rst expansion tool 101 is then retrieved and a second expansion tool 109, having a bladder 111 and tubular reinforcing member 113 which are longer than those of the first expansion tool 101, is secured to the work string 103 {Figure 8 (b )), The second expansion tool is run Into the tubular 117 and positioned as shown in Figure 9, with the blade 111 extending across the region of the tubular 123 which has been split and the transitional regions 125 which have been expanded but.hot played .

As shown in Figure 10, the bladder 111 is then expanded by injecting a settable medium 130 (such as epoxy) into the bladder through the tubular reinforcing member 113 and the settable medium allowed to settle, so as to seal the split 121 in the tubular 117. The second expansion tool is then disconnected from the work string 103 and dried through using a drill string (not shown) to establish a channel 132 through the tubular 117, as shown in Figure 11, During drilling, the tubular reinforcing member 113 functions as a guide for the drill string. In alternative embodiments, the method may be carried out using a single expansion tool. The straddle may be located in the region of a tubular which has been expanded and split by the expansion tool and released from a position around the work string above the expansion tool. that the expansion tool can be repositioned within the straddle and used to expand the straddle and seal the split in the tubular.

The method described above may be facilitated by the use of a tubular which is adapted to preferentially split along a weak zone. A length of tubular 200 having a series of weak zones 202 is shown in Figure 12. Each of the weak zones 202 is formed as a line which is machined axially along the tubular, where the thickness of the wall is the tubular. reduced by 80% compared to the tmmachined wail thickness (as can be seen in the cross sectional view of the tubular 200 of Figure 13). The weak: zones 202 are each surrounded by a. Further region £ 04 where the thickness of the wail is reduced by 80%. It will be understood that the: wail thickness of the tubular at or around the weak zone 202 may be reduced by a different percentage. In an alternative embodiment (not shown), the weak zone is provided by drilling, abrasive jetting, perforating (eg with shaped charges), or chemical etching, etc, apparatus in run into the tubular, and thus alternatively extending from the internal face of the tubular * rather than from the .external face as shown in Figures 12-14.

Extending along the length of the tubular and diametrically opposite the series of weak zones, is a predefined zone of deformation (not visible in Figure 12) .- As can be seen in Figure 13, the predefined zone of deformation 208 consists of a notch running axially along the tubular, extending to a depth o! 30% of the thickness of the wall of the .'tubular '200.

Figure 14 shows-the tubular 20Q in a bore 19, having been expanded and split by the · expansion tool 1 in the man! - described above and during the process of being extended towards the walls of the bore. Under the action of an expansion fool in the method described above, the tubular 200 splits along a weak zone 202 In a predictable fashion, in addition, as the further region of reduced wall thickness 204 is weaker than the adjacent portions of the wall of the tubular. The regions 204 bend outwardly, such that the torn edges of the weak zone 202 face away from the blade of the expansion tool. Thus, the tubular 200 is less prone to puncturing the bladder 5 of the expansion fool, In use.

As the tubular 200 is extended towards the wall of the bore (as described above) the walls of the tubular in the region of the tubular which have been split, preferably bend around the predefined zone of deformation 206. This increases the degree to which the torn edges of the weak zone 202 face away from the bladder 5 of the expansion tool 1, and also facilitates extension of the tubular 200 towards the bore 19, as shown in Figure 14. A tubular having weak zones (e. g. production tubing ) can be run into a bore and function normally and, if necessary (for example when water break through is detected) the apparatus shown in. Figure 1, which includes an expansion tool configured to expand the. tubular and at least one straddle positioned around a further expansion tool, can be run Into the bore and caused to split the tubular in a controlled fashion along one or more of the weak zones.

Figure 15 shoes a length of tubular 300 having circumferentially spaced apart weak zones 302a and 302b, diametrically opposite sides of the tubular, along a length 304 of the tubular. Figure 10 shoes a cross section of the tubular 300 along E, The weak zones 3028.0 are regions of reduced wall thickness. Alternative embodiments (not shown) circumferentially spaced apart weak zones may comprise a series of perforations.

The weak zones 302a and 302b may be provided in situ, for example by a mechanical drill or grinder positioned on the work strut, or by shaped charges: When the weak zones are created in situ, material will be taken away from the Inside rather than the outside of the tubular.

Figure 1? shows tubular 300, connected at each end to further tubulars 350, in art United bore 19. An expansion tool 401 connected to a work string (not shown) is located within the tubular 30D. The expansion, tool 401 has an inflatable bladder 407 and «.support member 413 extending within the inflatable bladder. An explosive charge 415 is positioned around the support member 413,

As shown in Figure 18, the bladder 40? may be rapidly expanded by detonating the explosive charge 415, causing the tubular 300 to split along the weak zones 302a and 302b (which are shown in Figures 15 and 16) and expand into engagement with the bore. Detonation of the explosive charge may cause bladder 407 to rupture into one or more portions 407a, h. The tool 401 may then be removed. A second expansion tool may then be run into the drill together with a straddle, such as to expand the straddle and seal the split tubular in the manner described above, with reference to Figures .5-11- in alternative embodiments (not shown). tubular may expand, split and break into fragments along the length of the tubular 300, and forced outwardly into engagement with the bore wall by the expanding bladder .. The portton (s) 407a, b of the ruptured bladder may then remain In .the bore 19 following: removal of the tooth 40 i, positioned so as to bridge between the fragments and the remainder of the tubular, and retain the fragments in position so as to prevent them from failing into the bore or into the tubular.

Claims (16)

A method of using to restrict or seal a borehole, comprising: expanding a tubular member disposed within the borehole to cause the tubular member to split and expand against a wall of the borehole, to place a connecting member within the tubular member which extends say over the part of the pipe element which has been split; and expanding the connector to seal the split portion of the tube member. The method of claim 1, comprising expanding the tubular member to cause the tubular member to split and expand to abut against a wall of the borehole. A method according to claim 1 or 2, wherein the borehole is provided by an additional pipe element or the borehole is provided by an open hole. A method according to any one of the preceding claims, comprising placing an expansion tool within the tube element and using the expansion tool to expand and split the tube element. The method of claim 4, wherein the expansion tool comprises a bladder and wherein the method comprises discharging the balloon. The method of claim 4 or 5, wherein the expansion tool comprises an explosive charge and wherein the method comprises detonating the explosive charge, thereby expanding and splitting the tubular member. A method according to any one of the preceding claims, comprising placing a connecting member positioned around the expansion tool and using the expansion tool to expand the connecting member and seal the split portion of the tubular member. A method according to any one of the preceding claims, comprising weakening a zone of the tubular member and subsequently splitting the tubular member along the weakened zone. The method of claim 8, comprising attenuating a zone of the tubular member in situ. An apparatus for use in restricting or sealing a borehole, comprising: an expansion tool which can be positioned within a tubular member disposed within the borehole and adapted to expand the tubular member; and causing the tubular member to split and expand against a wall of the borehole; and a connecting member which can be positioned within the pipe member and which may extend over a region of the pipe member which is split by the expansion tool, which connecting member is arranged to be radially expanded by an expansion tool so as to seal a split portion of the pipe member. An apparatus according to claim 10, comprising a first expansion tool adapted to expand the tubular member; and causing the tubular member to split and expand against a wall of the borehole; and another expansion tool adapted to radially extend the connector. 12. A pipe member having a weak zone extending axially along at least one of the length of the pipe member, said weak zone being arranged to preferably split under the influence of an expansion tool. The pipe element of claim 12, wherein the weak zone comprises a region of reduced wall thickness and / or wherein the weak zone comprises a series of perforations. The pipe element according to claim 12 or 13, comprising a predetermined deformation zone extending along at least part of the length of the pipe element and adapted to bend when the pipe element has been split and further expanded under the influence of an expansion tool. The pipe element according to claim 14, wherein the predetermined deformation zone and the weak zone are diametrically opposite to each other along at least part of the length of the pipe element. The pipe element according to claim 12 or 13, comprising two weak zones diametrically opposite to each other long at least a portion of the length of the pipe element.